def sum_2_num(num1, num2):
    """对两个数字的求和"""
    result = num1 + num2

    print("%d + %d = %d" %(num1, num2, result))
    return result
    # return 表示返回，下方的代码不会被执行到！
    num = 1000


sum_result = sum_2_num(10, 20);
print("计算结果：%d"% sum_result)